In studies of alcohol consumption in large and complex rat colonies we have found a number of rhythyms of alcohol consumption which do not occur in isolates, such as 2-5 day cycles of alcohol consumption which are negatively correlated with daily water intake, increases in alcohol consumption just prior to feeding and just prior to the beginning of the sleep cycle, and gradual increases in colony alcohol consumption from 12% of total fluid intake prior to lesioning to 34% of total fluid intake 25 days after the administration of monoamine neurotoxins. In both colony-housed and isolate-housed there were increases in alcohol consumption by animals administered by serotonin neurotoxin 5,6 DHT but decreases by animals administered the catecholamine toxin 6-OHDA. We now propose to determine the degree of intoxication achieved by individual colony rats during peak periods of alcohol consumption (as measured by behavioral and blood alcohol tests), the correlation of individual alcohol intake with standing in the dominance heirarchy, the role of "behavioral sinks" in alcohol intake, and the degree to which daily cycles of colony alcohol intake is due to caloric factors. We will compare individual differences in alcohol consumption in colony-housed and individually-caged animals. We will study the social interactions which just precede and just follow bouts of alcohol consumption in an effort to determine the antecedents and consequents of alcohol selection. In other studies we will investigate how alcohol consumption is altered by manipulations of central monoamine pathways produced by injections of neurotoxins, or localized brain lesions, or administration of stimulants. We will also develop a chronic slow-release alcohol administration system involving subcutaneous silicone capsules and compare the effects on subsequent alcohol self-selection, on brain neurochemistry, and on histology of brain cells of administering alcohol continuously throughout the 24 hr day as opposed to pulse administration of the same amount of alcohol, producing brief, extreme intoxication.